9 Answers
9

Generally, slow-cooking means any food preparation method which relies on using low-heat for a long amount of time. Barbecues, smokers, luau pits, and low-heat ovens could all qualify. The benefit of slow-cooking, generally, is that food becomes incredibly tender, as all of its connective tissues break down. Also, flavor can infuse over time and provide deeper results than with virtually any other method. Lastly, long-cooking times create a celebratory atmosphere where food is the focal point of a social gathering.

Specifically, slow-cooking refers to the 'slow-cooker' a counter-top set-up which has a large, electronically heated ceramic bowl and a glass lid. It usually has only a few settings, such as 'low', 'medium', and 'high'. The benefit of slow-cooking in a slow-cooker is mainly convenience. These units are safe enough to turn on before work and return to before dinner, with fully-cooked, piping hot food ready to go. The slow-cooker is geared towards 'one-pot' recipes, which means they require minimal food preparation. You simply cut up the ingredients in fairly large chunks, add seasoning, and liquid, and that's it. They are a favorite of working parents, but increasingly, also a device for more advanced experimentation.

The way I've heard the term "slow-cooking" used, it generally implies several things.

Cook times over 3 hours.

Stable, relatively low temperatures.

Some sort of wrapping or lid to trap the moisture inside.

A large amount of flavor exchange between ingredients.

The cooking vessel can be ceramic, cast iron pot, heated rock, regular oven, etc. The most important thing is that something is actively or passively regulating a constant, low cooking level.

However, when someone says "slow-cooker" in america, they are almost always referring to an electric crock pot, with a main earthenware vessel, glass lid, and basic temperature controls.

Although hot smoking can technically be a method for cooking food slowly in even heat, I haven't heard it referred to as "slow-cooking" because it's lacks the moisture trapping aspect.

Edit: Forgot about the second part of the question.

Slow cooking is good for cooking large things to an even level of doneness without drying out or burning.
It is great for dissolving the connective tissues in very tough cuts of meat and fibrous vegetables.
It is good for letting all the ingredients share flavors.
It is good for getting potatoes, beans, and pasta to dissolve into soups and stews.
It is not good for caramelizing or creating a Maillard reaction in foods.
It is not bad for keeping a crunchy texture.
It is not good for keeping flavors of ingredients separate and distinct.

You can also slow cook using a dutch oven. These are versatile enough to be used in the stove, but for a truly slow cook, you should bury it in the ground.

All you do is dig a hole wider and deeper than your oven, line the bottom with stones, and make a charcoal fire in it. Once your coals burn down put your oven on top (set some coals aside), put the remaining coals on top, and cover it in a few inches of dirt. About 6-8 hours later your food will be done. I've had some amazing pulled pork this way. :)

I'm a braising fanatic, and I can't stand those stupid counter top crock pot things. Small, erratic, unnecessary. Better to leave something cooking on your COUNTER than in your stove? I don't think twice about leaving a dutch oven in the stove overnight, at a low temperature. The stove is designed to contain high heat in the exact way that my counter top is not.

A good dutch oven is a must, if you don't have a convenient cooking pit, and learning to turn huge roasts that most people have only had has dry, hard to slice cinders, into melt-in-your-mouth delicious meat so moist and tender you can carve it with a spoon...It's a skill worth acquiring.

There's a big difference between small, cheap crock pots, and large, well-designed ones. On hot summer days, I prefer cooking roasts/hams/chickens in the crock pot to cooking in the oven because it doesn't heat up the kitchen anywhere near as much.
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Tim GilbertAug 3 '10 at 22:22

@cinque: In no way does the puppy endorse anything that might burn your house down. Always use caution with things that produce heat, etc, etc. If your meat is not wholly submerged, it'd be better if you were around to flip it at some point. Otherwise, doesn't matter.
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SatanicpuppyAug 4 '10 at 0:41

1

A good counter-top slow cooker should use significantly less electricity than an oven, for the same results.
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slimJan 12 '11 at 14:18

Slow cooking is done in a slow cooker or crock-pot. A description is found on Wikipedia here.

Basically it allows you to throw food in it and leave it to cook. It takes much longer to cook then on the stove or in the oven but you can leave it and forget about it while it is cooking. Most cookers allow you to set them to high or low and set a timer. If the timer runs out and you aren't there the automatic ones set it to warm so your food stays hot for when you get home. I don't recommend leaving it if you are cooking meat though.

Lorenzo, I've posted a question about slow cooking. When I use that term, I mean cooking in a particular cooker that has a ceramic bowl(s) with a lid and that can be left plugged into the electricity for long periods of time without worries.

The base of the slow cooker has a heating element that cooks the food in the ceramic bowls (crocks). It is very useful for people who work all day and want dinner done when they get home. This is because all the ingredients are added at once, the slow cooker is plugged in, and it cooks slowly throughout the day.

I even use mine when I'm home but don't want to bother watching my food cooking. I spend 4 months of the year in Lombardia but I don't remember seeing slow cookers there...but surely they are there.

Slow cooking is especially good for tough cuts of meat as they cook slowly and get very tender!

The one I have has 3 crocks...2 quarts, 4 quarts, and 6 quarts. One US liquid quart = 0.95 liters.

Some interesting answers here, only one of which even gets close to answering the question in my opinion.

What is slow cooking? As it says, it's cooking something over a long period of time.

What's it's good for? Now this is the key question. Why would you want to cook something for a long period of time if you could cook it quickly and get the same result?

What it's good for is tougher, less expensive cuts of meat that you cannot cook to a satisfying tenderness using quicker methods. To obtain the tenderness required, you have to cook it for a fairly long period of time.

The tougher the cut of meat, the longer you're going to have to cook it for.

Therefore I believe the correct answer you're looking for is, slow cooking is good for tough, cheap cuts of meat.

Slow cooking developed from a time when populations simply didn't have the financial resources to be able to afford the better, tender more expensive cuts of meat and had to make do with whatever they could afford and these were invariably less favoured, tougher cuts no-one else wanted. To make them edible, they cooked them on a low heat over a long period of time, hence slow cooking.

As others have said, slow cooking involves prolonged cooking at low temperatures. Meat starts to contract at temperatures past 100 degrees F and will begin to surrender its juices once it reaches 140 degrees. Cooking meat at a temperature between 130 and 140 degrees will allow collagen break-down whilst keeping the meat succulent.

Cooking at temperatures higher than 140 degrees will decrease cooking time, but the core temperature of the meat should not exceed 150 degrees. At 160 degrees it will be overcooked.

Update: There is a factual error in my answer above. Collagen starts to break down at around 160ºF (71ºC) so meat that is stewed will need to reach and maintain a temperature of at least 160ºF for 2 to 6 hours. The meat will only be 'succulent' if there is plenty of connective tissue (i.e. collagen) in the meat to begin with.